Mixture Of Meso Research Articles

A PH-functionalized dicationic bis(imidazolio)diphosphine.

Reaction of the iodide salt of a secondary imidazolio-iodophosphine [(L)PHI]I (L+ = 1,3-diarylimidazolium-yl) with an imidazolio-phosphide (L)PH in the presence of GaI3 afforded the isolable salt of a dicationic, bis(imidazolio)-substituted dihydro-diphosphine [(L)2P2H2][GaI4]2. Non-preparative formation of the cationic diphosphines was also observed upon spontaneous "dehalo-coupling" of [(L)PHI]+, or in reactions of [(L)PHI]I and (L)PH in the absence of GaI3. Further reaction of [(L)2P2H2]2+ with (L)PH produced an iodide salt of a known (bis)imidazolio-diphosphide monocation [(L)2P2H]+. The identity of cationic diphosphines and diphosphides was established by single-crystal X-ray diffraction studies. NMR spectroscopy revealed that dications [(L)2P2H2]2+ exist as a mixture of meso- and rac-diastereomers in solution. Computational studies confirmed the stereochemical assignment of the isomers observed, and gave insight into the bonding situation of the diphosphine dications.

Mussaenda frondosa L. mediated facile green synthesis of Copper oxide nanoparticles – Characterization, photocatalytic and their biological investigations

Green synthesis of Copper oxide nanoparticles (CuO-NPs) was achieved by using different parts of Mussaenda frondosa plant such as leaf, stem and leaf derived callus. Biofabricated CuO-NPs were characterized using Powder X- ray diffraction (XRD), Ultraviolet–visible spectroscopy (UV–Vis), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FTIR) and Dynamic light scattering (DLS) analysis. The XRD spectra confirmed the formation of pure monoclinical crystalline nature of CuO-NPs with an average grain size in the range of 2–10 nm. An extremely strong Surface Plasmon Resonance (SPR) between 300 and 400 nm distinctly reveals the synthesis of CuO-NPs. SEM and TEM analysis revealed the formation of spherical shaped agglomerated structures amidst large surface area. EDS spectra proved the existence of copper and oxygen elements in nanomaterials. FTIR spectra explained the possible bioactive molecules liable for the reduction of copper ions. DLS analysis and Zeta potential values validated the stability of CuO-NPs. The pore width distribution by the BJH plot indicates the mixture of meso as well as macropores with large surface area confirmed by BET analysis. Furthermore, the biofabricated NPs were investigated for photocatalytic and biological applications. CuO-NPs were found to exhibit potent DPPH radical scavenging activity. The cytotoxicity study was evaluated by MTT assay against Human lung cancer cell line (A549) and affirms the potent anticancer activity of CuO-NPs. The results of photocatalytic activity of methylene blue dye under UV- light depict 97.36% degradation at 140 min of illumination. Our studies illustrate facile green synthesis of CuO-NPs and found to possess significant biomedical and industrial applications.

Oligo-Aromatization of Light Hydrocarbons from Petroleum Refining Processes Over ZnO/MFI Microporous Material

The conversion of light hydrocarbons resulted as by-product of petroleum refining (mixtures of (n + i) butanes, 52.28 � 63.20 vol.%, (1-, cis-, trans-, 2-) butenes, 28.64 � 36.43 vol.% and propane � propylene, 4.79 � 14.64 vol.%) over bifunctional 5% ZnO/HZSM-5 co-catalyst in a fixed-bed stainless-steel reactor (Twin Reactor System Naky) at 450�C, 4 atm. total pressure and at a space velocity (WHSV) of 1 h-1 have been investigated. The results indicate that the selectivity to light aromatics � benzene, toluene and xylenes (BTX) � and to both the gaseous C1, C2 - C4 hydrocarbons and liquid (i + n) C5 � C10 aliphatic hydrocarbons depends on the time on stream of the process. This is a result of coke deposition (polyunsaturated compounds) and catalyst deactivation. The aromatics BTX represent 59-60 wt% in the liquid product during the first 24-36 hours time-on-stream and only 20-30 wt% after 40 hours of reaction when the aliphatic hydrocarbon C5 � C10 (mostly iso) and ]C10 (denoted �oligo�) reach to 70 � 80 wt%. The aromatic products were principally toluene, xylenes and benzene, theirs concentration varying with the time on stream of the process. The initial aromatization process described as dehydrocyclodimerization of alkanes and alkenes, principally to aromatics BTX and molecular hydrogen is accompanied by an oligomerization, isomerisation, cracking and alkylation process to form finally in the liquid product an excessively mixture of iso- and normal- C5 � C10 aliphatic hydrocarbons and ] C10.

INTERACTION IN POLYARYLATE – POLY(ARYLENE ETHER KETONE) MIXTURE AT HIGH-TEMPERATURE PROCESSING

Methods of modifying polyarylate based on bisphenol A and mixture of iso- and terephthalic acids by a representative of a promising class of polymers — polyarylene ether ketone have been discussed in this article. Comparative thermomechanical and thermofriction tests of two grades of poly(arylene ether ketone)based on bisphenol A and 4,4'-difluorobenzophenone (PAEK-32 and PAEK-34) have been carried out. It has been established that PAEK-34 is the most suitable for modifying polyarylate, which is confirmed by its higher softening temperature and stable friction coefficient at elevated temperatures. The thermomechanical properties and molecular mass distribution of amorphous polyarylene ether ketone before and after pressing have been studied. It has been established that during processing of poly(arylene ether ketone) PAEK-34 it’s molecular weight increases from 123 to 178 thousand a.m.u. with simultaneous change in the character of the molecular mass distribution from bimodal to unimodal. At the same time, there is a sharp decrease in the content of the low molecular weight fraction from 23.32 to 7.2%. Theoretical compatibility of polyarethylene ether ketone PAEK-34 and polyarylate DV based on the theory of solubility of substances has been studied. It was established that mixtures of these polymers are compatible for any components’ ratio according to the calculation results. The thermomechanical characteristics of the mixtures obtained on the basis of polyarylate and polyarylene ether ketone have been evaluated. It has been established that the growth of heat resistance of the mixture during processing is caused by intermolecular interaction of components with the formation of new chemical compounds having a block-type copolymer structure. This was confirmed by the change in the nature of the molecular-mass distribution of the polymer mixture upon the transition of the pressing temperature from 260 °C to 300 °C. It was established that the optimal conditions for the realization of block-copolymer formation reaction are created at 300 °C.

Palladium(ii) pincer complexes of a C,C,C-NHC, diphosphonium bis(ylide) ligand.

A new family of pincer palladium(ii) complexes bearing an electron-rich C,C,C-NHC, diphosphonium bis(ylide) ligand of LX2-type was prepared through the dual N-functionalization of 1H-imidazole by (3-bromopropyl)triphenylphosphonium bromide. Selected basic conditions allowed the sequential coordination of the NHC and phosphonium ylide moieties to Pd(ii). This strategy led to an original ortho-metallated complex where the Pd center is bonded to four carbon atoms of three different natures: carbenic (sp2), arylic (sp2), and chiral ylidic (sp3). Protonation of the latter afforded NHC, diphosphonium bis(ylide) pincer Pd(ii) complexes as a mixture of meso- and dl-diastereomers (de = 50%). The selectivity of C-coordination was rationalized on the basis of DFT calculations, evidencing the quasi-degeneracy of the two diastereomeric forms.

Synthesis and coordination chemistry of new asymmetric donor/acceptor pincer ligands, 1,3-C6H4(CH2PtBu(Rf))2 (Rf = CF3, C2F5).

Syntheses of new asymmetric pincer precursors 1,3-C6H4{CH2P(tBu,X)}2 (tBu,XPCPH; X = Cl, SiMe3, OPh) and a new class of hybrid donor/acceptor pincer ligands 1,3-C6H4{CH2P(tBu,Rf)}2 (tBu,RfPCPH; Rf = CF3, C2F5) are reported. All tBu,XPCPH compounds are obtained as mixtures of meso and rac diastereomers in varying ratios (meso : rac ∼ 4 : 1 to 3 : 2) which were used without separation. Treatment of Ru(cot)(cod) with tBu,CF3PCPH under 1 atm H2 in acetone at 20 °C produced the hydride solvate (tBu,CF3PCP)Ru(acetone)xH which was not isolated, but could be trapped as stable diene complexes (tBu,CF3PCP)Ru(L)2H (L2 = cod (1[combining low line]), nbd (2[combining low line])). Catalytic cyclooctane dehydrogenation studies demonstrate that 2[combining low line] has ∼50% the activity of (CF3PCP)Ru(cod)(H), but significantly higher catalyst stability and is able to operate at higher catalyst loading concentrations without deactivation via bimolecular decomposition.

Investigation of ecological parameters of four-stroke SI engine, with pneumatic fuel injection system

The publication presents the results of tests to determine the impact of using waste fuels, alcohol, to power the engine, on the ecological parameters of the combustion engine. Alternatively fuelled with a mixture of iso- and n-butanol, indicated with "X" and "END, and gasoline and a mixture of fuel and alcohol. The object of the study was a four-stroke engine with spark ignition designed to work with a generator. Motor power was held by the modified system of pneumatic injection using hot exhaust gases developed by Prof. Stanislaw Jarnuszkiewicz, controlled by modern mechatronic systems. Tests were conducted at a constant speed for the intended use of the engine. The subject of the research was to determine the control parameters such as ignition timing, mixture composition and the degree of exhaust gas recirculation on the ecological parameters of the engine. Tests were carried out using partially quality power control. In summary we present the findings of this phase of the study.

Fuel from waste animal fats

The hunger of the modern human society for energy is tremendous, which is increasing with the increasing population and with the pursuit of higher standards of living. A significant proportion of this energy demand is made up by the different fuels which ensure mobility. Based on environmental and energetic considerations, a larger proportion of this energy is trying to be covered with renewable energy sources on the whole world. Recently mankind utilised the first generation of biofuels for the transportation sector (bioethanol and biodiesel), but the development has not stopped. Today, the second generation is on the border of utilisation (2nd gen. bioethanol and bio gas oil – mixture of iso and normal paraffins). In this article, we are focusing on the topic of 2nd generation bio derived Diesel fuel, the so-called bio gas oil. We are investigating the possibilities of the utilisation of a new, waste feedstock, namely the brown greases which are the products of rendering facilities, in co-process with high sulphur containing heavy gas oil (1.2% sulphur content). During our experiments we produced bio gas oil containing gas oil fraction via the most favourable process parameters of hydrogenation (T: 330–340°C, p: 50bar, LHSV: 1.0h−1) and isomerisation (T: 340°C, p: 50bar, 1.0h−1) of waste lard containing gas oil stream. We determined that these kinds of waste fatty materials can be appropriate feedstocks for the production of renewable diesel–fuel components. In addition, these materials are cheap, and their iLUC (indirect land use change) value is practically zero. The properties (cetane number: ⩾54, CFPP: −10 to −20°C, yield: >91%) of the product obtained after the two consecutive process steps met the valid standard for diesel fuel, thus we proved that this kind of waste feedstock can be an option for bio derived engine fuel production.

Electroreductive dimerization of coumarin and coumarin analogues at carbon cathodes.

Electrochemical reduction of coumarin (1), 6-methylcoumarin (2), 7-methylcoumarin (3), 7-methoxycoumarin (4), and 5,7-dimethoxycoumarin (5) at carbon cathodes in dimethylformamide containing 0.10 M tetra-n-butylammonium tetrafluoroborate has been investigated by means of cyclic voltammetry and controlled-potential (bulk) electrolysis. Cyclic voltammograms for reduction of 1-5 exhibit two irreversible cathodic peaks: (a) the first peak arises from one-electron reduction of the coumarin to form a radical-anion intermediate, which is protonated by the medium to give a neutral radical; (b) although most of this radical undergoes self-coupling to yield a hydrodimer, reduction of the remaining radical (ultimately to produce a dihydrocoumarin) causes the second cathodic peak. At a potential corresponding to the first voltammetric peak, bulk electrolysis of 1-5 affords the corresponding hydrodimer as a mixture of meso and dl diastereomers. Although the meso form dominates, the dl-to-meso ratio varies, due to steric effects arising from substituents on the aromatic ring. Electroreduction of an equimolar mixture of 1 and 4 gives, along with the anticipated symmetrical hydrodimers, an unsymmetrical product derived from the two coumarins. A mechanistic scheme involving both radical-anion and radical intermediates is proposed to account for the formation of the various products.

Stereoisomeric products of electrochemical reduction of heterocyclic Fischer aminocarbene Cr(0) complexes. Development of the electrochemistry-mass spectrometry tandem approach using biphasic (acetonitrile-hexane) preparative electrolysis

Preparative electrolyses of a series of newly synthesized Cr(0) Fischer aminocarbene complexes bearing furane, thiophene or N-methylpyrrole rings attached by position 2 or 3, have been performed in acetonitrile. For the more friendly isolation of products and for better removal of conducting salt a biphasic preparative electrolysis was developed, where the electrolyzed acetonitrile solution is overlaid by hexane. This arrangement enables direct interconnection of the electrolyzed solution with a mass spectrometer. In all cases the only dominating products were dimeric species of the type N,N,N',N'-tetramethyl-1,2-di(hetaren-yl) ethane-1,2-diamine formed from two aminocarbene ligands after reductive splitting of the metallic part. Neither the type of heterocycle, nor its position of attachment influences the final products. Dimeric products of all studied aminocarbene complexes are electrochemically formed as a mixture of meso- and d,l- stereoisomers in a comparable representation. The stereoisomers were proved and characterized by MS and NMR, their separation was achieved by HPLC. The present contribution evidences the pure electrosynthetic approach to the above mentioned stereoisomers.

Metallacarborane clusters based on the middle-cage carborane [5,6-nido-C2B8H12]. Synthesis and the thermal isonido-to-closo rearrangement of the anionic complex [PPN][commo-1,1′-Rh(7-MeO-isonido-2,4-C2B8H9)-(isonido-2,4-C2B8H10)

The reaction of the middle-cage carborane 5,6-nido-C2B8H12 with the dimeric rhodium complexes [(η2-C8H14)2RhCl]2 or [(η4-C8H12)RhCl]2 in a MeOH/C6H6 mixture gave the anionic commo-rhodacarborane [PPN][commo-1,1′-Rh(isonido-2,4-C2B8H10)2] (as a mixture of meso and dd/ll isomers) and its 7-B-methoxylated derivative [PPN][commo-1,1′-Rh(7-MeO-isonido-2,4-C2B8H9)(isonido-2,4-C2B8H10)] in moderate yields. The latter was subjected to the thermal isonido-to-closo rearrangement to form the new commo-cluster [PPN][commo-1,1′-Rh(closo-2,3-C2B8H9OMe)(closo-2,3-C2B8H10)]. The newly synthesized compounds were characterized by NMR spectroscopy and X-ray diffraction.

Synthesis and Crystallographic Studies of Disubstituted Carboranyl Alcohol Derivatives: Prevailing Chiral Recognition?

The syntheses of new o-carboranyldiols bearing aromatic rings bis-[R(hydroxy)methyl]-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl 1a, 3-pyridyl 1b, 4-pyridyl 1c, 2-quinolyl 1d, 4-quinolyl 1e, phenyl 1f) are reported. The compounds are obtained as mixtures of meso (syn) and racemic (anti) stereoisomers with a slight diastereomeric excess (syn:anti ratio of 0.7:1) in all cases but in 1b. The crystal structures of the meso compounds syn-1a·2MeOH, syn-1b, syn-1f·0.25H2O and racemic anti-1a·MeOH, anti-1a·EtOH, and anti-1d·2H2O are reported. We provide an analysis of these compounds by means of NMR and X-ray crystallography, in the context of crystal engineering and chiral recognition. The results show that the crystal packings for these alcohols are dominated by the supramolecular O–H···N and/or O–H···O hydrogen bonds. Supramolecular analysis of all compounds in this work reveals that homochiral self-assembly, that is, formation of homochiral hydrogen bonded complexes, prevails over heterochiral self-assembly...

Synthesis and application of head-to-head-type styrene dimers bearing two fluoroalkyl end-groups

Head-to-head-type styrene and substituted styrene dimers bearing two fluoroalkyl end-groups have been efficiently synthesized by a simple reaction of perfluoroalkyl iodide with styrene under radical conditions as a mixture of meso and racemic forms. The meso form obtained from the mixture by recrystallization gave a crystal suitable for X-ray diffraction study and the crystal structure was found to be based on π-stacking of benzene rings and aggregation of fluoroalkyl chains. Dynamic light scattering measurements showed that meso-styrene dimers bearing two fluoroalkyl end-groups can form the nanometer size-controlled self-assemblies through the intermolecular π-stacking of benzene rings and aggregation of end-capped fluoroalkyl groups in methanol.

Formation and Structure of a Platinum(II) Complex Containing TwotransNonstabilized Phosphorus Ylide Ligands: Evidence for Reversible Ylide Dissociation

The reaction of (nBu4P)2[PtBr4] with 2,2′-(C6H4Li)2 yields selectively (by 195Pt and 31P NMR) the compound trans-PtBr2[CH(nPr)(PnBu3)]2 as a mixture of meso (R,S) and dl (R,R + S,S) diastereoisomers. The initially formed 1:1 mixture slowly evolves toward a solution richer in the meso compound, which then crystallizes selectively. In addition to the NMR characterization, the meso isomer has also been characterized by a single-crystal X-ray diffraction analysis. DFT calculations in the gas phase and in solution (THF) confirm the slight thermodynamic preference for the meso isomer and reproduce the chemical shift difference of the 195Pt NMR resonances. They also suggest the likelihood of a dissociative mechanism for the slow diastereoisomer interconversion.

ChemInform Abstract: Determination of Enantiomeric Purity of Alcohols Using Achiral Diphenyldichlorosilane.

Abstract Diphenyldichlorosilane was used as a dimerization agent to convert enantiomeric alcohols to a mixture of meso and dl diastereomeric silyl acetals. The meso and dl compounds can be distinguished by 13 C NMR method and their ratio can be used to evaluate the optical purity of the alcohols.

From Functional Phospholide Ions to Bifunctional 1,1′-Diphosphaferrocenes

Both the 2-ethoxycarbonyl and the 2-benzoyl phospholides (1 and 2) react with FeCl2 in the presence of ZnCl2 to give the corresponding 2,2′-difunctional 1,1′-diphosphaferrocenes as mixtures of meso and rac diastereomers. Stable rotamers are also detected by 1H and 13C NMR spectroscopy. Under the same conditions, the 2,5-bis(ethoxycarbonyl)phospholide (3) gives the tetrafunctional 1,1′-biphospholyl (6). The diphosphaferrocenes and the 1,1′-biphospholyl are probably formed from a common type of intermediates with a bis(η1-phospholyl)iron structure. DFT computations indicate that this kind of intermediate is pyramidal at P and only weakly aromatic.

Structural Characterization of Eight Cyclic Lipopeptides Produced By Bacillus subtilis HSO121

Lipopeptides are amphiphilic compounds which contain both hydrophobic fatty acid moieties and amphiphilic peptide moieties. From the cell-free broth of Bacillus subtilis HSO121, eight cyclic lipopeptides were isolated by reversed-phase high performance liquid chromatography (RP-HPLC). The peptide part of each lipopeptide was elucidated according to electrospray ionization quadruple-time-of-flight mass spectrometry (ESI Q-TOF MS) and the fatty acid part was analyzed by electroionization gas chromatography/mass spectrometry (EI GC/MS). It showed that fractions 1-8 had molecular masses of 1007, 1021, 1021, 1035, 1035, 1035, 1063, and 1049, respectively. Analysis of hydrolyzed lipopeptides revealed that they had invariant amino acid compositions. The differences in molecular weights represent changes in the number of methylene groups and different types of branched chains in fatty acids. Peptide sequences of two of the eight lipopeptides appeared to be N-Asp-Leu-Leu-Val-Glu-Leu-Leu-C, which was different from previously reported lipopeptides. The remaining six had an identical peptide sequence of N-Glu-Leu-Leu-Val-Asp-Leu-Leu-C. The fatty acid parts were found to be mixtures of iso C(12), iso C(13), anteiso C(13), iso C(14), n C(14), iso C(15), anteiso C(15), n C(15), anteiso C(16) and anteiso C(17) beta-hydroxy fatty acids. The structure of each lipopeptide was determined to be the beta-hydroxy fatty acid bonded to the peptide chain.

Rhenium Analogues of Promising Renal Imaging Agents with a {99mTc(CO)3}+ Core Bound to Cysteine-Derived Dipeptides, Including Lanthionine

The coordination chemistry of lanthionine (LANH2) and cystathionine (CSTH2) dipeptides, which respectively consist of two cysteines and one cysteine and one homocysteine linked by a thioether bridge, is almost unstudied. Recently for fac-[99mTc(CO)3(LAN)]- isomers, the first small 99mTc(CO)3 agents evaluated in humans were found to give excellent renal images and to have a high specificity for renal excretion. Herein we report the synthesis and characterization of Re complexes useful for interpreting the nature of tracer 99mTc radiopharmaceuticals. Treatment of [Re(CO)3(H2O)3]OTf with commercially available LANH2 (a mixture of meso (d,l) and chiral (dd,ll) isomers) gave three HPLC peaks, 1A, 1B, and 1C, but treatment with CSTH2 (l,l isomer) gave one major product, Re(CO)3(CSTH) (2). Crystalline Re(CO)3(LANH) products were best obtained with synthetic LANH2, richer in meso or chiral isomers. X-ray crystallography showed that these dipeptides coordinate as tridentate N2S-bound ligands with two dangling carboxyls. The LANH ligand is meso in 1A and 1C and chiral in 1B. While 1A (kinetically favored) is stable at ambient temperature for days, it converted into 1C (thermodynamically favored) at 100 degrees C; after 6 h, equilibrium was reached at a 1A:1C ratio of 1:2 at pH 8. The structures provide a rationale for this behavior and for the fact that 1A and 1C have simple NMR spectra. This simplicity results from fluxional interchange between an enantiomer with both chelate rings having the same delta pucker and an enantiomer with both chelate rings having the same lambda pucker. Agents with the [99mTc(CO)3]+ core and N2S ligands show promise of becoming an important class of 99mTc radiopharmaceuticals. The chemistry of Re analogues with these ligands, such as the LAN2- complexes reported here, provides a useful background for designing new small agents and also tagged large agents because two uncoordinated carboxyl groups are available for conjugation with biological molecules such as proteins.

Synthesis and structure determination of stereoisomeric 2,2’-dibenzoyl-3,3’,4,4’-tetramethyl-1,1’-diphosphaferrocenes

Reaction of 3,3’,4,4’-tetramethyl-1,1’-diphosphaferrocene 1 with an excess of benzoyl chloride and AlCl3 afforded a ~1:1 mixture of meso- and rac-2,2’-dibenzoyl-3,3’,4,4’-tetramethyl-1,1’diphosphaferrocenes 2, which were separated by column chromatography. The less polar diastereomer was transformed into its bis-W(CO)5- complex 3. The single crystal X-ray study revealed that this complex contains the meso-2 ligand. Therefore, the more polar diastereomer must be rac-2. It has been suggested that the splitting pattern of the phospholyl protons signal in the 1 H NMR spectra can be used for stereochemistry assignments.

Synthesis, Characterization, and Catalytic Properties of ansa‐Zirconocenes [Zr{1‐Me2Si(3‐η5‐C9H5R)2}Cl2] (R = Me, nPr, nBu, and Bz)

AbstractThe ansa‐indene ligands {1‐Me2Si(3‐C9H6R)2} [R = Me (1), nPr (2), nBu (3), and Bz (4)] were prepared by alkylation of the unsubstituted ansa‐indene. These ligands were converted, by reaction with nBuLi, to the di‐lithium compounds [Li2{1‐Me2Si(3‐C9H5R)2}] [R = Me (5), nPr (6), nBu (7), and Bz (8)]. ansa‐Zirconocenes, [Zr{1‐Me2Si(3‐η5‐C9H5R)2}Cl2] [R = Me (9), nPr (10), nBu (11), and Bz (12)], have been prepared by the reaction of ZrCl4 with 5–8 in diethyl ether/toluene at–78 °C. The molecular structure of meso‐[Zr{1‐Me2Si[3‐η5‐C9H5(CH3)]2}Cl2] (9) and rac‐[Zr{1‐Me2Si[3‐η5‐C9H5(CH2CH2CH3)]2}Cl2] (10) have been determined by single‐crystal X‐ray diffraction studies. Ethylene polymerization catalysis has been studied for complexes 9–12 as a mixture of meso and rac isomers in the presence of methylaluminoxane (MAO) as cocatalyst. Complexes 9–12 exhibit high activities and give rise to polyethylene with low molecular weights without the introduction of molecular hydrogen. In addition, active species from these complexes were found to be very stable in comparison with unsubstituted analogues.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)